ABAP CDS - 字符串函数

下表显示了ABAP CDS中CDS视图中字符串的潜在SQL函数，以及对参数的要求。函数的含义可以在字符串的SQL函数下找到。

函数	参数类型	返回类型
CONCAT(arg1, arg2)	See below	SSTRING if an argument has the type SSTRING, else CHAR with the length of the result.
CONCAT_WITH_SPACE(arg1, arg2, spaces )	arg1, arg2: see below spaces: positive numeric literal greater than 0 and less than or equal to 1331	SSTRING if an argument has the type SSTRING, else CHAR with the length of the result.
INSTR(arg, sub)	arg: see below sub: non-empty numeric literal	INT4
LEFT(arg, len)	arg: see below len: positive numeric literal greater than 0 and less than or equal to 1333	SSTRING if arg has the type SSTRING, else CHAR with length len
LENGTH(arg)	See below	INT4
LPAD(arg, len, src)	arg: see below len: positive numeric literal greater than 0 and less than or equal to 1333 src: character Literal	SSTRING if arg has the type SSTRING, else CHAR with length len
LTRIM(arg, char)	arg: see below char: Character literal with length 1	SSTRING if arg has the type SSTRING, else CHAR with the length of arg.
REPLACE(arg1, arg2, arg3)	See below	SSTRING if arg1 or arg3 has the type SSTRING, else CHAR with the maximum possible length of the result.
RIGHT(arg,len)	arg: see below len: positive numeric literal greater than 0 and less than or equal to 1333	SSTRING if arg has the type SSTRING, else CHAR with length len
RPAD(arg, len, src)	arg: see below len: positive numeric literal greater than 0 and less than or equal to 1333 src: character literal	SSTRING if arg has the type SSTRING, else CHAR with length len
RTRIM(arg, char)	arg: see below char: Character literal with length 1	SSTRING if arg has the type SSTRING, else CHAR with the length of arg.
SUBSTRING(arg, pos, len)	arg: see below pos and len: positive numeric literal not equal to zero	SSTRING, if arg has the type SSTRING, else CHAR or NUMC with a length of at least len

以下可以指定为参数:

• suitable类型的文字。文本可以以域名作为前缀。

• 当前CDS视图的数据源数据源的适当字段。

• 用于标识数据源数据源的适当字段的路径表达式。

• 从参数列表中输入 parameters.

• 以下预定义的函数和表达式（如果它们返回匹配的类型）：

• 其他预定义的SQL函数

• 算术表达式

• Type modifications using CAST

arg、arg1、arg2和arg3的有效参数类型为char、clnt、lang、numc、cuky、unit、dats、tims和sstring。

在指定了显式长度len的函数中，当CDS视图被激活时，结果的实际长度被定义为至少和len一样长。

在除lpad和rpad之外的所有函数中，所有参数的尾随空格在实际处理之前被删除，结果的尾随空格在返回操作之前被删除。在lpad和rpad中，参数src的尾随空格被保留。

注释

系统代码页utf-16的代理区域中的字符由cds字符串函数作为两个字符处理。在确定长度时必须遵守这一点，并且这些字符不能被错误地拆分。

例子

以下CDS视图将选择列表中字符串的预定义SQL函数应用于数据库表demo_表达式的列。程序演示光盘的SQL函数字符串使用select访问视图。

@AbapCatalog.sqlViewName: 'DEMO_CDS_STRFUNC'
@AccessControl.authorizationCheck: #NOT_REQUIRED
  define view demo_cds_sql_functions_string
   as select from demo_expressions
   { length(            char1               ) as r_length,
     instr(             char1, 'CD'         ) as r_instr,
     concat(            char1, char2        ) as r_concat,
     concat_with_space( char1, char2, 10    ) as r_concat_with_space,
     left(              char1, 3            ) as r_left,
     right(             char2, 3            ) as r_right,
     lpad(              char1, 10, 'x'      ) as r_lpad,
     rpad(              char2, 10, 'y'      ) as r_rpad,
     ltrim(             char1, 'A'          ) as r_ltrim,
     rtrim(             char1, 'E'          ) as r_rtrim,
     replace(           char2, 'GHI', 'XXX' ) as r_replace,
     substring(         char2, 2, 3         ) as r_substring }

SQL函数的字符串

下表显示了abap cds和open sql支持的字符串的SQL函数。最后两列指示函数的使用位置。

SQL 函数	结果	ABAP CDS	Open SQL
CONCAT(arg1, arg2)	Chaining of character strings in arg1 and arg2. Trailing blanks in arg1, arg2, and in the result are ignored. The maximum length of the result is 1333.	x	x
CONCAT_WITH_SPACE(arg1, arg2, spaces )	Concatenation of strings in arg1 and arg2 as with CONCAT. The number of blanks specified in spaces is inserted between arg1 and arg2. The maximum length of the result is 1333.	x	-
INSTR(arg, sub)	Position of the first occurrence of the string from sub in arg (case-sensitive). arg respects leading blanks and ignores trailing blanks. sub respects all blanks. sub must contain at least one character. If no occurrences are found, the result is 0.	x	-
LEFT(arg, len)	String of the length len with the len left characters of arg (ignoring the trailing blanks). The value of len cannot be greater than the length of arg.	x	-
LENGTH(arg)	Number of characters in arg ignoring trailing blanks.	x	x
LPAD(arg, len, src)	String of the length len with the right-justified content of arg without trailing blanks and in which leading blanks produced by the expanded string are replaced by the characters from the argument src (respecting all blanks). Trailing blanks from arg are preserved. If more characters are required than exist in src, the content of src is used repeatedly. If len is less than the length of arg, it is truncated on the right. If src is empty and len is greater than the length of arg, arg remains unchanged.	x	x
LTRIM(arg, char)	String with the content of arg in which all trailing blanks are removed and all leading characters that match the character in char. A blank in char is significant.	x	x
REPLACE(arg1, arg2, arg3)	Character string arg1, in which all instances of arg2 are replaced by the content from arg3. The replacement of letters is case-sensitive. Trailing blanks are ignored in all arguments. The maximum length of the result is 1333.	x	x
RIGHT( arg, len )	String of the length len with the len right characters of arg (ignoring the trailing blanks). The value of len cannot be greater than the length of arg.	x	x
RPAD(arg, len, src)	String of the length len with the left-justified content of arg without trailing blanks and in which trailing blanks produced by the expanded string are replaced by the characters from the argument src (respecting all blanks). Trailing blanks from arg are preserved. If more characters are required than exist in src, the content of src is used repeatedly. If len is less than the length of arg, it is truncated on the right. If src is empty and len is greater than the length of arg, arg remains unchanged.	x	-
RTRIM(arg, char)	String with the content of arg in which all trailing blanks are removed and all trailing characters that match the character in char. A blank in char is significant.	x	x
SUBSTRING(arg, pos, len)	Substring of arg from the position pos in the length len. pos and len must be specified so that the substring is within in arg.

关于潜在操作数和数据类型的描述可以在ABAPCDS和OpenSQL的相应文档中找到。

参考文章

ABAP CDS - String Functions

SQL Functions for Strings

本文原始地址：https://www.cnblogs.com/yjyongil/p/10495142.html